Sanding device

ABSTRACT

attached to the surface. A handle (C) is attached to one edge of the blade (A) in order to stiffen the blade (A) so that the blade is stiff around one axis lying in a plane normal to the plane of the blade and normal to the handle and is flexible around an axis normal to the plane of the blade and parallel to the handle. The sanding device facilitates abrasion of surfaces in corners and rebates without undesirably abrading the adjacent surface.

This invention relates to a device for abrading detailed surfaces and surfaces of abradable material, especially, but not limited to, surfaces formed of wood in difficult to reach areas, examples are edges, corners, grooves, and small areas of a flat surface.

BACKGROUND

Sanding a large flat surface is straightforward and many known devices achieve a satisfactory result. Difficulties arise when sanding right up to an edge of an adjacent vertical surface or into a corner with adjacent vertical surfaces on two sides. A good example is sanding a cupboard door where the typically recessed central panel meets with the raised framed sides known as rails and stiles. When faced with these difficult areas, powered sanders, where the sanding abrasive surface oscillates at high speed, bounce out of the corners and off the raised adjacent surfaces, providing a poor abraded finish and often damage the adjacent surfaces. For this reason, much detail sanding is undertaken by hand. There are two common devices for hand sanding corners and other detail. These are 1: A sanding block, typically made of wood or another rigid material, rectilinear in shape with square edges and corners, is fitted by the operator with abrasive paper, or 2: A foam sanding pad usually of a rectangular box shape comprised of a firm foam coated with a fixed abrasive finish.

A sanding block is held in the hand or by the hand using a handle. The area being sanded has to be large enough to accommodate the entire sanding block with additional room for the operator to move the sanding block from side to side whilst also applying pressure in order to provide the abrasive effect. A sanding block will only sand into a corner if there is

areas that the sanding block can access usefully because the attachment hardware obstructs effective sanding of detail and edges. Worn abrasive paper attached to a sanding block is replaced in its entirety even when parts of the abrasive paper are not yet entirely worn, this is particularly prevalent when sanding into corners and edges where the operator is applying pressure to address these particular areas.

Sanding Pads operate in a similar manner as the sanding block, the primary difference being that a sanding pad is not rigid as it is constructed from firm foam coated with an abrasive finish often applied to all planer surfaces of the pad. Because foam is used in the construction of a sanding pad, sanding pads have some flexibility. The flexibility is provided by the foam, and while useful, particularly on curved surfaces, this flexibility does not always address square corners as well. Because the sanding pad is flexible square edges can mistakenly be rounded if the operator applies too much pressure to the sanding pad when sanding square profiles and inside corners, both can be left less than square due to the lack of rigidity of the sanding pad. Sanding pads are expensive compared to sanding blocks. Once a sanding pad is worn the entire device is discarded. Often the edges of a sanding pad are worn long before the planer sides are completely worn. Sanding pads are available in various grades of abrasive and therefore a variety of abrasive graded blocks are required by the operator, which in turn requires a larger area of storage to stock the variety of sanding pads that might be needed for any given sanding task. Some sanding pads have multiple grades of abrasive on each facet. These are not always applicable to a given job and many go unused.

We are aware of an example of a sanding device described in British patent GB 1205267 (Diversified Invest Company S A) which shows a sanding device in the shape of a file, the device including a rectangular blade formed of flexible material, one element of a hook and loop fastener being secured to a face of the blade; and an abrasive sheet having an abrasive face and the other element of the hook and loop faster carried on its opposite face.

STATEMENT OF THE INVENTION

According to a first aspect of the present invention, there is provided a sanding device comprising:

a blade formed of resiliently flexible material, the blade having a long edge and a short edge adjacent the long edge; one element of a hook and loop fastener secured to a face of the blade and extending from the long edge; and an abrasive sheet having an abrasive face and the other element of the hook and loop faster carried on its opposite face, characterized by means for restricting the flexibility of the blade about an axis at right angles to the long edge.

According to a second aspect of the invention, there is provided a method of sanding a surface, using a sanding device according to the first aspect of the invention, including the steps of applying the device to the surface with the abrasive face against the surface,

By the term “blade” as used herein, we mean an element having a generally flat shape, with some straight edges and a narrow profile, i.e. a thickness substantially less than the other dimensions thereof. A blade having sharp edges (as in a cutting tool) is not envisaged. The blade may be rectangular, triangular or of other polygonal shape. To overcome limitations of and provide an alternative to existing hand sanding devices, the present invention proposes a rectangular hand-held blade with a hook fastening on one side of the blade for attaching hook & loop fastened abrasive paper. Abrasive papers with a fastening face opposite the abrasive face and bearing one of the hook or loop fastening material are widely available. The blade is preferably rectilinear with a long edge having a dimension of 60 to 250 mm, at least one shorter edge, adjacent the long edge, having a dimension of 50 to 100 mm and a thickness of 0.5 to 6.0 mm. The ratio of the length of the long edge to the thickness of the blade is preferably between 50:1 and 100:1, for example 75:1.

The blade is preferably formed of a plastics material, such as polypropylene or polycarbonate.

The means for restricting the flexibility of the blade preferably comprises a bar secured to or formed integrally with the blade. The bar may constitute a handle which is preferably elongate and extends in a direction substantially parallel to the long edge of the blade, that is within an angle of no more than ±20° to the long edge of the blade. Preferably, the handle is integral with the blade, and made of the same material as the blade but of greater thickness to reduce its flexibility. Preferably the handle has a thickness from 2 to 3

width axis and is therefore substantially more flexible across its depth axis. Thus the blade will flex easily around an axis lying in a plane perpendicular to the plane of the blade and a long axis of the stiffening structure and, is relatively stiff around an axis perpendicular to the plane of the blade and parallel to the long axis of the stiffening structure. This asymmetric flex provides a sprung pressure to the leading abrasive edge of the device when the operator bends the blade against a surface, or the device can provide a flat straight abrasive surface when the operator does not employ the sprung pressure. The operator can easily manage the required sprung pressure of the device when in use without stopping the process of abrading a surface.

Preferably the ratio of stiffness for the depth direction to the bar direction is between 1.25 and 5. In other words the force, applied to an edge of the blade, required to deflect the blade by a specific amount in each direction, per unit length of the blade, in the respective direction, is at least 1.25 times more in the bar direction than in the depth direction and preferably not more than 6 times. Stiffness is measured in the absence of the sanding paper.

Although the term paper is used, any flexible sheet abrasive material may be understood to fall within the scope of the term, eg emery cloth.

The blade may be an homogenous material of uniform thickness so that the difference is directional stiffness is achieved solely by means of the stiffening bar. A preferred blade

abrasive surface that can utilise the sprung pressure of bending the blade to abrade thoroughly into corners, up against adjacent surfaces and across small areas of flat surface. The flexibility of the blade is used to direct sprung pressure downwards (i.e. towards the workpiece being abraded) at the abrasive end of the device where the abrasive paper is mounted. In use, the abrasive paper is abrading only the surface it is facing, any adjacent vertical surfaces can be worked directly up against without being damaged or abraded. Dependant on the sprung pressure applied, the abraded area is up to approximately 4 cm out from the placement of the abrasive end of the blade, leaving the corners and edges of a surface well sanded while avoiding damage to adjacent areas, so that other devices can be employed to sand any remaining large easy to access areas adjacent to these already abraded areas.

Alternatively, the abrasive paper can be wrapped around the long edge of the blade to allow sanding into a straight narrow groove or other routed detail where the square sanding of one, two or three facets is required.

The device makes very economical use of the abrasive paper. As only the edge of the abrasive paper wears, the abrasive paper can be removed, and the worn section squarely cut off with scissors or a knife and the remainder of the abrasive paper reattached so that newly cut and unworn section of the same abrasive paper sheet now forms the fresh abrasive edge on the device, thus gaining the maximum use from a single sheet of abrasive paper.

create abrasion where as other sanding devices would require the operator to get their hand or fingers behind the device to create abrasive pressure and very a tight space will not provide sufficient room for this.

In addition to edge and detail sanding, the device can be used to abrade smaller flat areas. When the sprung nature of the blade is not employed the blade is substantially flat. In this state the device is particularly good at sanding smaller flat areas such as the edges of cupboard doors, long lengths of routed detail, intricate profiles and small proud areas that need to be made flat, as is the requirement when sanding a repair made with filler.

The device can easily be made in a portable form and is advantageously more compact than a conventional sanding block or pad, thus occupying minimal space in a tool box. This is also an advantage in terms of packaging, transport and display.

The device can easily be made in a lightweight form. While the device is most conveniently manufactured as an integral plastics structure, it may be formed from more durable materials such as metals, for example steel or stainless steel.

The device can be made in a form which is very small compared to other sanding devices, not much larger than the abrasive sheets attached to it. It can be stored in a very small amount of space.

In use therefore, the device is typically held in the palm of the hand with the operator's four fingers at the back of the blade and the thumb to the abrasive side or vice-versa.

in other materials. Examples of abradable materials include wood, metal and alloys, stone, plaster, plastics materials and mixtures thereof. The devices are particularly suitable for abrading surfaces formed of wood.

As will be apparent to one skilled in the art from the accompanying description and drawings, sanding devices according to preferred embodiments of the invention incorporate a handle to provide rigidity along the width of the blade ensuring that the blade does not flex along the axis of its width but can flex along the axis of its depth, in that the flexibility of the blade is limited to providing sprung pressure along the depth of the blade only. The sanding device utilises the sprung energy of bending the blade to provide pressure for abrading surfaces. The sanding device abrades surfaces tightly up to adjacent edges and corners. The sanding device can abrade one plane of an inside corner without sanding the adjacent plane(s). The sanding device utilises its thin profile to abrade surfaces in difficult to reach places. The sanding device utilises its thin profile to abrade narrow grooves on one, two, or all three facets of a groove or other linear detail typically found on furniture mouldings. The sanding device utilises its flat profile to sand flat areas.

INTRODUCTION TO THE DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows a sanding device according to the invention without any abrasive paper

hook fastener strip set squarely along the abrasive edge;

FIG. 4 shows the sanding device of FIG. 2 being applied to a flat surface panel recessed within a frame;

FIG. 5 shows the sanding device of FIG. 2 being used in a difficult to reach flat space between a kitchen unit and a refrigerator;

FIG. 6 shows the sanding device according to the invention being used to sand all three facets of a groove in tongue and groove panelling;

FIG. 7 is a profile drawing of the sanding device of FIG. 2 being used to sand a surface right up to the corner with adjacent surface; and

FIG. 8 shows the sanding device of FIG. 2 being applied to a wooden mirror frame attached to a wooden backboard.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Referring to the drawings, FIG. 1 shows the sanding device according to the invention without any abrasive paper attached. The device comprises a generally rectilinear blade (A), formed of moulded polypropylene and having a 115 mm long edge (E), a 100 mm short edge (X) forming an angle 90° with the long edge (E) and a thickness of 1.5 mm, a hook fastener strip (B) that is the hook component of a hook & loop fastener and is permanently fixed to one side of the blade (A). The other side of the blade (A) is bare and has no hook fastener strip. Starting from the abrasive straight long edge (E), the hook fastener strip (B) extends across the full width of the blade (A) and to just over half the depth of the blade (A). This is preferable, although the hook element (B) could extend

of the blade so that there is no flexibility in the blade across its width. The blade (A) is intended to only flex along the depth axis which runs between the abrasive edge (E) and the handle (C). The handle (C) also provides comfort to the palm when held in the operator's hand, typically when in use the handle rests across the palm as seen in FIG. 4. The device is rarely if ever actually held by the handle (C) when in use.

As shown in FIG. 2, the abrasive paper (D) is mounted onto the hook fastener strip (B) of the device. The abrasive paper (D) is backed by the loop component of a hook & loop fastening.

As shown in FIG. 3, the device with the abrasive paper (D) is mounted to the hook fastener strip (B) set squarely along the abrasive edge (E).

As shown in FIG. 4 in use the device is applied to a flat surface wood panel recessed within a frame, also known as the stile or rail, as is common in the construction of a cupboard door. The semi-flexible nature of the blade (A) is used by the operator to apply sprung pressure to the surface of the abrasive paper (D) and this pressure is strongest at the abrasive edge (E). Given that the abrasive edge (E) is straight, sanding can be performed squarely up to the inside corner of an adjacent edge (F) or into a corner (G). Given that the sprung pressure provided by the blade (A) is maximised at the abrasive edge (E) the device can perform effective sanding right up to adjacent edges (F) and inside corners (G).

space where the operator's fingers are unable to reach. The smooth side of the blade (A) faces the fridge, the sprung pressure available in the blade (A) is used lightly in this instance in combination with utilising the flat profile of the blade. The kitchen side panel is sanded by the abrasive paper (D) while the fridge is not exposed to the abrasive paper (D) despite the very tight space.

As shown in FIG. 6 the device can be used to sand all three facets of a groove in some tongue and groove panelling. In this instance the abrasive paper (D) has been wrapped around the end of the abrasive edge (E) of the blade (A), the abrasive paper (D) is held secure by the hook fastener strip (B) on one side and the operator's fingers on the opposite and smooth side of the blade (A), thus allowing all three sides of the abrasive edge (E) of the blade (A) to sand in the groove. As the abrasive paper (D) on the abrasive edge (E) becomes worn, the abrasive paper (D) is removed and an unused section of the same sheet of abrasive paper (D) is set around the abrasive edge (E). This process can continue until the entire area of the abrasive paper (D) is worn to depletion.

As shown in FIG. 7 the device can be used to sand the surface (Z) right up to the corner with adjacent surface (Y), without abrading the surface (Y).

As shown in FIG. 8 the device can be applied to a wooden mirror frame (T) attached to a wooden backboard (V). A mirror (M) is mounted to the backboard (V) via screws set close to the mirror frame (T). One screw (S) can be seen in the illustration. The semi-flexible nature of the blade (A) is used by the operator to apply the sprung pressure of the device to the abrasive paper (D) allowing the operator to sand the surface of the frame (T) right

meet. The head of the domed screw (S) would generally restrict access to sanding the corner if power sanders, sanding blocks or sanding pads were in use. In this example, the screw (S) is not an obstruction to sanding the surface of the frame (T) because of the thin profile of the device allows the device to access and abrade the frame (T) with even pressure just as thoroughly as if the screw (S) was not present.

In summary, the described and illustrated embodiments of the invention provide a hand-held blade (A), planer in shape, typically the size of a post card, mounted with abrasive paper (D) to one side by means of hook and loop fastenings (B). The flexibility of the blade (A) is restricted across its entire width by a rigid handle (C) fixed across the top and the full width of the blade (A). The flexibility of blade (A) is not restricted in the longitudinal direction in the same manner to allow it to flex thereby allowing the operator to apply sprung pressure from the flexible blade (A) down the length of the blade (A), through the abrasive paper (D) mounted along the abrasive edge (E) of the blade. In use the abrasive edge (E) is used for abrading tightly into edges, detail and corners or when not under sprung pressure, applied flat to abrade smaller flat areas. 

1. A sanding device comprising a resiliently deformable blade (A), one element (B) of a hook and loop fastener formed on one planar surface of the blade (A) whereby an abrasive sheet provided with the complementary element of a hook and loop fastener can be secured to the blade (A), characterized by a stiffening structure (C) at one edge of the blade (A) to stiffen the blade (A) so that the blade will flex easily in a plane perpendicular to the plane of the blade and a long axis of the stiffening structure and is relatively stiff perpendicular to the plane of the blade and parallel to the long axis of the stiffening structure.
 2. A sanding device according to claim 1 comprising: the blade is formed of a material to be resiliently flexible.
 3. A sanding device according to claim 1 comprising the blade having a long edge and a short edge adjacent the long edge; the element of a hook and loop fastener secured to a face of the blade and extending from the long edge.
 4. A sanding device according to claim 1 comprising: an abrasive sheet (D) having an abrasive face and the other element of the hook and loop faster carried on its opposite face.
 5. A sanding device according to claim 3, wherein the short edge of the blade forms an angle of no more than 90° with the long edge.
 6. A sanding device according to claim 1, wherein the stiffening structure (C) for restricting the flexibility of the blade comprises a bar formed integrally with the blade and having a thickness greater than that of the blade.
 7. A sanding device according to claim 6, wherein the bar is in the form of a handle secured to the blade.
 8. A sanding device according to claim 6, wherein the bar is elongate and extends in a direction substantially parallel, as herein defined, to the long edge of the blade.
 9. A sanding device according to claim 1, wherein the blade is rectangular.
 10. A sanding device according to claim 1, wherein the blade is formed of polypropylene or polycarbonate.
 11. A sanding device according to claim 1, wherein the ratio of the length of the long edge of the blade to the thickness of the blade is between 50:1 to 100:1
 12. A sanding device according to claim 11 wherein the ratio of the length of the long edge of the blade to the thickness of the blade is 75:1
 13. A sanding device according to claim 1, wherein the ratio of specific stiffness of the blade in each said direction is between 1.25 and
 6. 14. A method of sanding a surface, using a sanding device according to any previous claim, including the steps of applying the device to the surface with the abrasive face against the surface, applying hand pressure to the device in a region away from the long edge thereby to cause the blade to flex while moving the device in a plane parallel to the surface, thereby to abrade the surface. 